U.S. patent application number 13/564314 was filed with the patent office on 2013-02-07 for pneumatic tire.
This patent application is currently assigned to The Yokohama Rubber Co., LTD. The applicant listed for this patent is Masahiro Ishida, Hiraku Kouda. Invention is credited to Masahiro Ishida, Hiraku Kouda.
Application Number | 20130032265 13/564314 |
Document ID | / |
Family ID | 47554354 |
Filed Date | 2013-02-07 |
United States Patent
Application |
20130032265 |
Kind Code |
A1 |
Kouda; Hiraku ; et
al. |
February 7, 2013 |
PNEUMATIC TIRE
Abstract
A pneumatic tire with a side wall portion includes a decorative
region including two or more decorative portions that are
continuously disposed so as to be contiguous in a tire
circumferential direction and the tire radial direction, the
decorative portions including multiple convex ridges that are
disposed on an outer surface so as to be adjacent in the tire
circumferential direction. A ridge arrangement angle is the same in
the same decorative portion, and a ridge arrangement angle of the
contiguous decorative portion differs therefrom. A distance between
a first imaginary boundary line joining end portions of the ridges
of the decorative portion that are on a side adjacent to the
contiguous decorative portion and a second imaginary boundary line
joining end portions of the ridges of the contiguous decorative
portion on a side adjacent to the first imaginary boundary line is
less than 1 mm.
Inventors: |
Kouda; Hiraku;
(Hiratsuka-shi, JP) ; Ishida; Masahiro;
(Hiratsuka-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kouda; Hiraku
Ishida; Masahiro |
Hiratsuka-shi
Hiratsuka-shi |
|
JP
JP |
|
|
Assignee: |
The Yokohama Rubber Co.,
LTD
Tokyo
JP
|
Family ID: |
47554354 |
Appl. No.: |
13/564314 |
Filed: |
August 1, 2012 |
Current U.S.
Class: |
152/523 |
Current CPC
Class: |
B60C 13/001 20130101;
B60C 13/02 20130101 |
Class at
Publication: |
152/523 |
International
Class: |
B60C 13/02 20060101
B60C013/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2011 |
JP |
JP 2011-170535 |
Claims
1. A pneumatic tire comprising a tread portion, a side wall
portion, and a bead portion, wherein the side wall portion
comprises, in a specific region in a tire radial direction, a
decorative region including two or more decorative portions that
are continuously disposed so as to be contiguous in a tire
circumferential direction and the tire radial direction,
respectively, the decorative portions including multiple convex
ridges that are disposed on an outer surface so as to be adjacent
in the tire circumferential direction; a ridge arrangement angle,
which is an angle formed by the ridges and a line tangent to the
decorative region at an edge on an inner side in the tire radial
direction, is the same in the same decorative portion, and a ridge
arrangement angle of the contiguous decorative portion differs
therefrom; and a distance between a first imaginary boundary line
joining end portions of the ridges of the decorative portion that
are on a side adjacent to the contiguous decorative portion and a
second imaginary boundary line joining end portions of the ridges
of the contiguous decorative portion on a side adjacent to the
first imaginary boundary line is less than 1 mm.
2. The pneumatic tire according to claim 1, wherein the first
imaginary boundary line and the second imaginary boundary line are
disposed periodically in the tire circumferential direction and the
tire radial direction.
3. The pneumatic tire according to claim 1, wherein the ridge
arrangement angle of the decorative portion is not less than
20.degree. and not more than 160.degree. different from the ridge
arrangement angle of the contiguous decorative portion.
4. The pneumatic tire according to claim 1, wherein the decorative
region includes not less than three types and not more than twelve
types of the decorative portions having different ridge arrangement
angles.
5. The pneumatic tire according to claim 1, wherein the decorative
portions are disposed in the decorative region in the tire
circumferential direction and/or the tire radial direction in a
combination where the ridge arrangement angle varies
periodically.
6. The pneumatic tire according to claim 1, wherein an area of a
decorative portion is not less than 0.3 cm.sup.2 and not more than
10.0 cm.sup.2.
7. The pneumatic tire according to claim 1, wherein at least one of
the decorative portions included in the decorative region has a
ridge length per unit area different than the ridge length per unit
area included in the decorative portions.
8. The pneumatic tire according to claim 1, wherein the ridges of
the decorative portion are separated from the ridges of the
contiguous decorative portion.
9. The pneumatic tire according to claim 1, wherein the two or more
decorative portions comprises not less than three of the decorative
portions.
10. The pneumatic tire according to claim 1, wherein an arrangement
pitch of the ridges is not less than 0.5 mm and not more than 5.0
mm.
11. The pneumatic tire according to claim 1, wherein the two or
more decorative portions comprise at least one of a rectangular
decorative portion, a pentagonal decorative portion, and a
decorative portion that is partially curved so as to be contiguous
around a triangular decorative portion.
12. The pneumatic tire according to claim 1, wherein the ridges of
the decorative portion are not separated from the ridges of the
contiguous decorative portion.
13. The pneumatic tire according to claim 1, wherein the decorative
portions are disposed in rows in the tire circumferential
direction.
14. The pneumatic tire according to claim 1, wherein the decorative
portions are disposed in rows in the tire radial direction.
15. The pneumatic tire according to claim 1, wherein the decorative
portions are disposed in order of stepwise ascending or descending
size of the ridge arrangement angle.
16. The pneumatic tire according to claim 1, wherein the imaginary
boundary lines overlap.
17. The pneumatic tire according to claim 1, wherein the decorative
region is provided throughout all regions of the side wall portion
of the tire.
Description
PRIORITY CLAIM
[0001] Priority is claimed to Japan Patent Application Serial No.
2011-170535 filed on Aug. 3, 2011.
BACKGROUND
[0002] 1. Technical Field
[0003] The present technology relates to a pneumatic tire for
mounting on a vehicle.
[0004] 2. Related Art
[0005] Pneumatic tires for mounting on vehicles such as automobiles
and the like are known that have a portion (serration) in a side
wall portion of the tire where multiple ridges are formed at a
short pitch, the ridges being constituted by small, linear
protrusions or recesses. For example, in Japanese Patent No.
3645358, a pneumatic tire in which a circular decorative body is
provided on a surface of a side wall is described, the circular
decorative body being formed from multiple small ridges having a
height of not more than about 2 mm, disposed at a small pitch of
not more than about 5 mm in a circumferential direction.
Additionally, with the pneumatic tire described in Japanese Patent
No. 3645358, the circular decorative body is divided into a
plurality of crescentic decorative bodies on the periphery by a
narrow band-like dividing band that extends in a direction inclined
at a large angle, with respect to a radial direction, of not less
than 70.degree. and less than 90.degree.. The ridges extend
substantially parallel to each other within the same crescentic
decorative body, and extend in a different direction in a
contiguous crescentic decorative body.
[0006] Additionally, in Japanese Unexamined Patent Application
Publication No. H06-106921A, a pneumatic tire is described in which
a side wall portion is divided into a plurality of fan-shaped
regions in a tire circumferential direction, wherein a difference
between surface roughness of contiguous fan-shaped regions is not
less than 50 .mu.m.
[0007] As with the pneumatic tire described in Japanese Patent No.
3645358, appearance flaws of a tire can be improved by forming a
serration in the side wall of the tire, the serration being
constituted by multiple ridges. However, with the pneumatic tire
described in Japanese Patent No. 3645358, unevennesses in the side
wall portion of the tire, specifically at carcass splice portions
and portions where the carcass is folded up, may not be
sufficiently camouflaged. Thus, there are cases where improvement
of the quality of the appearance of the tire is insufficient.
Additionally, in some cases, camouflaging properties are
insufficient even when the surface roughness for each region
divided into a plurality of sections in the circumferential
direction is varied, as described in Japanese Unexamined Patent
Application Publication No. H06-106921A and, thus, improvement of
the quality of the appearance of the tire may be insufficient.
SUMMARY
[0008] The present technology provides a pneumatic tire by which
the quality of the appearance of the tire can be enhanced while
maintaining performance of the tire. The present technology
includes a pneumatic tire including a tread portion, a side wall
portion, and a bead portion. The side wall portion includes, in a
specific region in a tire radial direction, a decorative region
including two or more decorative portions that are continuously
disposed so as to be contiguous in a tire circumferential direction
and the tire radial direction, respectively, the decorative
portions including multiple convex ridges that are disposed on an
outer surface so as to be adjacent in the tire circumferential
direction. A ridge arrangement angle, which is an angle formed by
the ridges and a line tangent to the decorative region at an edge
on an inner side in the tire radial direction, is the same in the
same decorative portion, and a ridge arrangement angle of the
contiguous decorative portion differs therefrom. A distance between
a first imaginary boundary line joining end portions of the ridges
of the decorative portion that are on a side adjacent to the
contiguous decorative portion and a second imaginary boundary line
joining end portions of the ridges of the contiguous decorative
portion on a side adjacent to the first imaginary boundary line is
less than 1 mm.
[0009] Unevennesses at carcass splice portions and portions where
the carcass is folded up are more appropriately camouflaged due to
the providing of the decorative region in which a plurality of
decorative portions having ridge arrangements that are different
from those of the contiguous decorative portions is disposed in the
tire circumferential direction and the tire radial direction,
respectively, in the side wall portion. Therefore, it is possible
to realize a superior three-dimensional appearance of the pneumatic
tire. As a result, the quality of the appearance of the tire can be
enhanced while maintaining performance of the tire.
[0010] Here, the first imaginary boundary line and the second
imaginary boundary line are preferably disposed periodically in the
tire circumferential direction and the tire radial direction. By
periodically disposing the first imaginary boundary line and the
second imaginary boundary line, each of the decorative portions can
be provided with a similar or substantially identical form and
unevennesses in the side wall portion can be more appropriately
camouflaged. Therefore, it is possible to realize a superior
three-dimensional appearance of the pneumatic tire.
[0011] Additionally, the ridge arrangement angle of the decorative
portion is preferably not less than 20.degree. and not more than
160.degree. different from the ridge arrangement angle of the
contiguous decorative portion. By varying the ridge arrangement
angle a certain angle or greater, unevennesses in the side wall
portion can be more appropriately camouflaged and a superior
three-dimensional appearance of the pneumatic tire can be
realized.
[0012] Additionally, the decorative region preferably includes not
less than three types and not more than twelve types of the
decorative portions having different ridge arrangement angles. As a
result, unevennesses at carcass splice portions and portions where
the carcass is folded up can be more appropriately camouflaged and
a superior three-dimensional appearance of the pneumatic tire can
be realized.
[0013] Additionally, the decorative portions are preferably
disposed in the decorative region in the tire circumferential
direction and/or the tire radial direction in a combination where
the ridge arrangement angle varies periodically. As a result, a
superior three-dimensional appearance of the pneumatic tire can be
realized.
[0014] Additionally, an area of a decorative portion is preferably
not less than 0.3 cm.sup.2 and not more than 10.0 cm.sup.2. As a
result, unevennesses at carcass splice portions and portions where
the carcass is folded up can be more appropriately camouflaged and
a superior three-dimensional appearance can be realized.
[0015] Additionally, preferably at least one of the decorative
portions included in the decorative region has a ridge length per
unit area different than the ridge length per unit area included in
the decorative portions. As a result, unevennesses at carcass
splice portions and portions where the carcass is folded up can be
more appropriately camouflaged and a superior three-dimensional
appearance can be realized.
[0016] Additionally, ridges of the decorative portion are
preferably separated from ridges of the contiguous decorative
portion. As a result, cracking can be more favorably suppressed and
durability can be enhanced.
[0017] According to the pneumatic tire of the present technology, a
pneumatic tire by which the quality of the appearance of the tire
is enhanced while maintaining performance of the tire can be
provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a side view of a pneumatic tire according to an
embodiment of the present technology.
[0019] FIG. 2 is an explanatory drawing illustrating a portion of a
decorative region of the pneumatic tire depicted in FIG. 1.
[0020] FIG. 3 is an enlarged side view illustrating the decorative
region further enlarged.
[0021] FIG. 4 is an enlarged side view illustrating an area around
a boundary between decorative portions.
[0022] FIG. 5A is an explanatory drawing illustrating a portion of
another example of the decorative region.
[0023] FIG. 5B is an explanatory drawing illustrating a portion of
another example of the decorative region.
[0024] FIG. 5C is an explanatory drawing illustrating a portion of
another example of the decorative region.
[0025] FIG. 5D is an explanatory drawing illustrating a portion of
another example of the decorative region.
[0026] FIG. 5E is an explanatory drawing illustrating a portion of
another example of the decorative region.
[0027] FIG. 5F is an explanatory drawing illustrating a portion of
another example of the decorative region.
[0028] FIG. 6 is an enlarged side view illustrating another example
of an area around a boundary between decorative portions.
[0029] FIG. 7 is an enlarged side view illustrating another example
of an area around a boundary between decorative portions.
[0030] FIG. 8 is an enlarged side view illustrating another example
of a decorative region of the pneumatic tire.
[0031] FIG. 9 is an enlarged side view illustrating another example
of a decorative region of the pneumatic tire.
DETAILED DESCRIPTION
[0032] An embodiment of the present technology is described below
in detail based on the drawings. However, the present technology is
not limited to this embodiment. The constituents of the embodiment
include constituents that can be easily replaced by those skilled
in the art and constituents substantially same as the constituents
of the embodiment. Furthermore, the multiple modified examples
described in the embodiment can be combined as desired within the
scope apparent to a person skilled in the art.
[0033] In the following descriptions, additionally, "tire width
direction" refers to a direction parallel to a rotational axis (not
illustrated) of a pneumatic tire 1, and "outer side in the tire
width direction" refers to a side distanced from a tire equatorial
plane (tire equator) in the tire width direction. "Tire
circumferential direction" refers to a circumferential direction
with the rotational axis as the center axis. Furthermore, "tire
radial direction" refers to the direction orthogonal to the
rotational axis; "inner side in the tire radial direction" refers
to the side facing the rotational axis in the tire radial
direction; and "outer side in the tire radial direction" refers to
the side distanced from the rotational axis in the tire radial
direction. Additionally, "tire equatorial plane" refers to a planar
surface orthogonal to the rotational axis and that passes through a
center of a tire width of the pneumatic tire 1. The tire width is
the width in the tire width direction between constituents located
to the outside in the tire width direction, or in other words, the
distance between the most distant constituents from the tire
equatorial plane in the tire width direction. Furthermore, "tire
equator" refers to a line along the circumferential direction of
the pneumatic tire 1 that lies on the tire equatorial plane.
[0034] FIG. 1 is a side view of a pneumatic tire according to an
embodiment of the present technology. FIG. 2 is an explanatory
drawing illustrating a portion of a decorative region of the
pneumatic tire depicted in FIG. 1. FIG. 3 is an enlarged side view
illustrating the decorative region further enlarged. FIG. 4 is an
enlarged side view illustrating an area around a boundary between
decorative portions. As illustrated in FIG. 1, the pneumatic tire 1
includes a tread portion 2 that is in contact with a road surface;
a side wall portion 3 that is assembled on a rim 6 and is visible
on the outermost side in the tire width direction of the pneumatic
tire 1 when mounted on a vehicle; and a bead portion 4 that
interlocks with this rim 6 when the pneumatic tire 1 is assembled
on the rim 6.
[0035] As illustrated in FIGS. 1 and 2, the side wall portion 3 has
a decorative region (serration portion) 5 on a surface thereof. The
decorative region 5 is formed in a shape that extends along the
tire circumferential direction within a predetermined range in the
tire radial direction of the side wall portion 3 or, in other
words, in a circular shape. The decorative region 5 is
fundamentally provided in a predetermined region in the tire radial
direction, that is, in a region including a position outermost in
the tire width direction, at a position of an end portion where a
carcass (not illustrated), which constitutes a skeleton of the
pneumatic tire 1, is folded over the bead portion 4, and
overlapping portions of the carcass (carcass splice portions).
[0036] As illustrated in FIG. 2, the decorative region 5 is a toric
region surrounded by an outer ring 52 and an inner ring 53. Note
that in FIG. 2, only a portion having a constant width in the tire
circumferential direction of the decorative region 5 is depicted,
but, as illustrated in FIG. 1, the decorative region 5 is disposed
throughout all regions in the tire circumferential direction. The
outer ring 52 and the inner ring 53 are circles having a center of
the pneumatic tire 1 in the radial direction as centers.
Additionally, the outer ring 52 is a circle with a diameter greater
than that of the inner ring 53.
[0037] The decorative region 5 is divided into a plurality of
sections by multiple imaginary boundary lines 32 and multiple
imaginary boundary lines 34. The imaginary boundary lines 32 are
straight imaginary lines extended in the tire radial direction and
are formed at a constant pitch in the tire circumferential
direction. First end portions of the imaginary boundary lines 32
are located at the outer ring 52 and second end portions are
located at the inner ring 53. In other words, the imaginary
boundary lines 32 are straight lines extending from edge to edge of
the decorative region 5 in the tire radial direction. The imaginary
boundary lines 34 are imaginary lines that are extended in the tire
circumferential direction and are concentric with the outer ring 52
and the inner ring 53, and are formed at a constant pitch in the
tire radial direction.
[0038] As described above, the decorative region 5 is divided into
a plurality of sections in the tire radial direction by the outer
ring 52, the inner ring 53, and the imaginary boundary lines 34,
and is divided into a plurality of sections in the tire
circumferential direction by the imaginary boundary lines 32. In
the decorative region 5, each section surrounded in the tire
circumferential direction by two of the imaginary boundary lines
34, the imaginary boundary line 34 and the outer ring 52, or the
imaginary boundary line 34 and the inner ring 53; and surrounded in
the tire radial direction by two of the imaginary boundary lines 32
constitutes a decorative portion 22. Thus, a plurality of the
decorative portion 22 is disposed in rows throughout an entire
circumference in the tire circumferential direction, and a
plurality of the decorative portion 22 is disposed in rows in the
tire radial direction in the decorative region 5 of this
embodiment. Note that the number of the decorative portions 22
constituting the decorative region 5 is not particularly limited
provided that not less than two of the decorative portions are
provided in the tire circumferential direction and the tire radial
direction, respectively. Preferably, not less than three of the
decorative portions are provided in the tire circumferential
direction and the tire radial direction, respectively.
[0039] The decorative portion 22 includes a plurality of ridges 23.
Note that in FIG. 2, the ridges 23 of a part of the decorative
portions 22 are depicted with cross-hatching, and depiction of the
ridges 23 in other decorative portions 22 is omitted. The ridges 23
are protrusions that protrude in the tire width direction, and
extend in any single direction on the tire surface. The plurality
of ridges 23 of the decorative portion 22 is disposed in rows, in a
direction orthogonal to the extending direction thereof.
Additionally, an angle (hereinafter referred to as the "ridge
arrangement angle .alpha.") formed by a straight line and a line
tangent to the inner ring 53 at a contact point between a line
extended from a straight line of the ridges 23 and the inner ring
53 (hereinafter also referred to as the "ridge starting point") is
the same angle. Note that in cases where the ridges are curved
lines or the like, an angle formed by a straight imaginary line
joining the starting point and ending point of the ridge and the
line tangent to the inner ring 53 is the ridge arrangement
angle.
[0040] Here, it is sufficient that the imaginary boundary lines 32
and 34 are imaginary lines that demarcate the edges of the
decorative portions 22, and need not be formed so as to be actually
visible on the decorative portions 22. The imaginary boundary lines
32 and 34 are lines that join end portions (end portions on a first
side or end portions on a second side) of the ridges 23 formed in
the corresponding decorative portion 22. In other words, the
imaginary boundary lines are imaginary lines that join the end
portions of ridges having the same ridge arrangement angle, and
constitute boundaries between decorative portions having different
ridge arrangement angles. Additionally, the imaginary boundary
lines 32 and 34 are lines that overlap with the ridge 23 farthest
to the edge of the corresponding region in cases where the
imaginary boundary lines 32 and 34 are parallel with the ridges 23.
In other words, in cases where the imaginary boundary line of the
ridges 23 of the decorative portion is parallel with the ridges 23
of the contiguous decorative portion, the ridge 23 closest to the
imaginary boundary line of said decorative portion is the imaginary
boundary line. That is, an imaginary line joining a first end and a
second end of the closest ridge 23 is the imaginary boundary
line.
[0041] Next, the decorative portions 22 will be explained in more
detail using FIG. 3. Note that in FIG. 3, decorative portions 22a,
22b, 22c, 22d, 22e, 22f, 22g, and 22h, which are in a portion on
the inner ring 53 side, of the decorative portions 22 of the
decorative region 5 are depicted. A boundary on the inner side in
the tire radial direction of the decorative portions 22a, 22b, 22c,
22d, 22e, 22f, 22g, and 22h is the inner ring 53, and a boundary on
the outer side in the tire radial direction (boundary with another
decorative portion 22) is the imaginary boundary line 34.
Additionally, a boundary between contiguous decorative portions in
the tire circumferential direction of the decorative portions 22a,
22b, 22c, 22d, 22e, 22f, 22g, and 22h is the imaginary boundary
line 32. For example, the decorative portion 22a and the decorative
portion 22b are divided in the tire circumferential direction by
the imaginary boundary line 32.
[0042] The decorative portion 22a includes a plurality of ridges
23a. An angle (ridge arrangement angle) formed by the ridges 23a
and the line tangent to the inner ring 53 at the ridge starting
point, which is a contact point between the inner ring 53 and an
extended line of the ridges 23a, is an angle .alpha..sub.1. The
ridge arrangement angle .alpha..sub.1 in this embodiment is
67.5.degree.. Thus, depending on the position where the ridges 23a
are formed, the angle formed with the line tangent to the inner
ring 53 at the ridge starting point varies. Therefore, a shape is
formed in which a distance between adjacent ridges 23a increases
from the inner ring 53 toward the outer ring 52. Note that with the
ridges 23a illustrated in FIG. 3, the ridges extend to a position
contacting the inner ring 53, but in cases where the end portions
of the ridges 23a on the inner ring 53 side do not contact the
inner ring 53, specifically, in cases where the end portions
contact imaginary boundary lines 32 and 34, it is sufficient that
extended lines of the ridges 23 satisfy the ridge arrangement angle
.alpha..
[0043] Note that in this embodiment, the ridge arrangement angle of
each of the ridges 23a is set at the angle .alpha..sub.1, but the
ridges 23a may be disposed so as to be aligned in a mutually
parallel manner so that the angle (ridge arrangement angle) formed
with the line tangent to the inner ring 53 at the ridge starting
point, which is a contact point between the inner ring 53 and an
extended line of one ridge 23a of the plurality of ridges 23a, is
the angle .alpha..sub.1. That is, the ridges 23a formed in the
decorative portion 22a may be disposed in parallel, and the ridge
arrangement angle of one arbitrary ridge 23a thereof may be
configured to be the ridge arrangement angle .alpha..sub.1 of the
ridges 23a of the decorative portion 22a.
[0044] Additionally, the ridges 23a are disposed at a spacing so
that a distance between adjacent ridges 23a (arrangement pitch,
distance in a direction orthogonal to the extending direction of
the ridges 23a) is constant. Here, the arrangement pitch of the
ridges is preferably not less than 0.5 mm and not more than 5.0 mm.
When the arrangement pitch of the ridges is within the range
described above, the ridges can be disposed at an appropriate
spacing in the decorative region.
[0045] The decorative portion 22b includes a plurality of ridges
23b. The ridge arrangement angle of the ridges 23b is an angle
.alpha..sub.2. The ridge arrangement angle .alpha..sub.2 in this
embodiment is 45.degree.. The decorative portion 22c includes a
plurality of ridges 23c. The ridge arrangement angle of the ridges
23c is an angle .alpha..sub.3. The ridge arrangement angle
.alpha..sub.3 in this embodiment is 22.5.degree.. The decorative
portion 22d includes a plurality of ridges 23d. The ridge
arrangement angle of the ridges 23d is an angle .alpha..sub.4. The
ridge arrangement angle .alpha..sub.4 in this embodiment is
0.degree.) (180.degree.. The decorative portion 22e includes a
plurality of ridges 23e. The ridge arrangement angle of the ridges
23e is an angle .alpha..sub.5. The ridge arrangement angle
.alpha..sub.5 in this embodiment is 157.5.degree.. The decorative
portion 22f includes a plurality of ridges 23f. The ridge
arrangement angle of the ridges 23f is an angle .alpha..sub.6. The
ridge arrangement angle .alpha..sub.6 in this embodiment is
135.degree.. The decorative portion 22g includes a plurality of
ridges 23g. The ridge arrangement angle of the ridges 23g is an
angle .alpha..sub.7. The ridge arrangement angle .alpha..sub.8 in
this embodiment is 112.5.degree.. The decorative portion 22h
includes a plurality of ridges 23h. The ridge arrangement angle of
the ridges 23h is an angle .alpha..sub.8. The ridge arrangement
angle .alpha..sub.8 in this embodiment is 90.degree..
[0046] One unit of the decorative region 5 is constituted by the
eight decorative portions, decorative portion 22a to decorative
portion 22h, and said unit is disposed continuously in the tire
circumferential direction. That is, a first side of the decorative
portion 22a in the tire circumferential direction is contiguous
with the decorative portion 22b via the imaginary boundary line 32,
and a second side in the tire circumferential direction is
contiguous with the decorative portion 22h via the imaginary
boundary line 32. Additionally, the decorative portions 22 that are
sandwiched between the imaginary boundary line 34 and the imaginary
boundary line 34, and the decorative portions 22 that are
sandwiched between the imaginary boundary line 34 and the outer
ring 52; that is, the decorative portions 22, which are farther to
the outer side in the tire radial direction than the decorative
portions 22a to 22h illustrated in FIG. 3, have a ridge arrangement
angle that is an angle different than that of the decorative
portion that is contiguous thereto in the tire circumferential
direction.
[0047] Additionally, in the decorative region 5, the ridge
arrangement angles of the decorative portion and the decorative
portion that is contiguous with said decorative portion in the tire
radial direction are different angles. In other words, with the
decorative portions 22, just as with the decorative portions 22
that are contiguous in the tire circumferential direction, the
decorative portions 22 that are contiguous in the tire radial
direction also have different ridge arrangement angles.
[0048] Next, a relationship of the ridges of two contiguous
decorative portions near the imaginary boundary line will be
explained using FIG. 4. Note that a relationship of the ridges of
two contiguous decorative portions near the imaginary boundary line
is the same. Therefore, the relationship at the imaginary boundary
line 132 between the ridges 123 of the decorative portion 122a and
the ridges 125 of the contiguous decorative portion 122b is
described below, being representative of relationships near the
imaginary boundary line of the ridges of two contiguous decorative
portions. The decorative portion 122a and the decorative portion
122b are two contiguous decorative portions that were arbitrarily
extracted from the decorative region. As illustrated in FIG. 4,
first end portions of the ridges 123 of the decorative portion 122a
extend to the imaginary boundary line 132. Additionally, second end
portions of the ridges 125 of the decorative portion 122b extend to
the imaginary boundary line 132. In other words, the imaginary
boundary line 132 is a line joining the first end portions of the
ridges 123 of the decorative portion 122a and is a line joining the
second end portions of the ridges 125 of the decorative portion
122b. As illustrated in FIG. 4, the ridges 123 of the decorative
portion 122a are formed at positions that do not overlap with the
ridges 125 of the decorative portion 122b. Specifically, the ridges
123 of the decorative portion 122a are formed at positions
different from those of the ridges 125 of the decorative portion
122b, and even though the end portions of both ridges are
positioned on the imaginary boundary line 132, the first end
portions of the ridges 123 of the decorative portion 122a do not
overlap with the second end portions of the ridges 125 of the
decorative portion 122b.
[0049] As described above, the decorative region 5 has a structure
in which multiple decorative portions 22 are disposed in rows in
the tire circumferential direction and the tire radial direction,
respectively. Additionally, the ridge arrangement angle .alpha. of
one of the decorative portions 22 is different than the ridge
arrangement angle .alpha. of a contiguous decorative portion 22.
Therefore, when the imaginary boundary lines 32 and 34 are passed
through the decorative region 5, the ridge arrangement angles
.alpha. will differ. That is, the imaginary boundary lines 32 and
34 are boundaries and, in the decorative region 5, with each of the
imaginary boundary lines 32 and 34, the ridge arrangement angle of
the ridges on a first side and the ridge arrangement angle of the
ridges on the second side thereof are different angles.
[0050] The pneumatic tire 1 has the configuration described above
and the decorative region 5, in which a plurality of decorative
portions that satisfy the conditions described above are
continuously provided in the tire circumferential direction and the
tire radial direction, respectively, is provided in regions
including the position outermost in the tire width direction, at a
position of an end portion where a carcass (not illustrated), which
constitutes a skeleton of the pneumatic tire 1, is folded over the
bead portion 4, and overlapping portions of the carcass (carcass
splice portions). Therefore, bulges on the surface of the side wall
portion 3 where the carcass is folded over and at the carcass
splice portions can be made unnoticeable while enhancing the
appearance of the outermost side in the tire width direction (the
side wall portion 3) by the decorative portions 22 constituting the
decorative region 5.
[0051] Furthermore, in the pneumatic tire 1, a plurality of the
decorative portions that satisfy the conditions described above are
continuously provided in the tire circumferential direction and the
tire radial direction, respectively, in the decorative region 5.
Therefore, effects of making bulges on the surface of the side wall
portion 3 where the carcass is folded over and at the carcass
splice portions unnoticeable can be more preferably obtained.
Furthermore, in the pneumatic tire 1, a plurality of the decorative
portions that satisfy the conditions described above are
continuously provided in the tire circumferential direction and the
tire radial direction, respectively, in the decorative region 5.
Therefore, the three-dimensional appearance of the side wall
portion 3 can be further improved.
[0052] As described above, in the pneumatic tire 1, a plurality of
the decorative portions are continuously provided in the tire
circumferential direction and the tire radial direction,
respectively, in the decorative region 5 and, furthermore, the
ridge arrangement angle .alpha. of one of the decorative portions
is configured to differ from the ridge arrangement angle .alpha. of
each of the contiguous decorative portions. Therefore, variations
in light reflection can be caused between decorative regions,
unevennesses in the side wall portion 3 caused by carcass splice
portions and portions where the carcass is folded up can be
camouflaged and made unnoticeable, and the tire can be made to
appear more three-dimensional.
[0053] In the embodiment described above, the imaginary boundary
lines that divide the decorative portions constituting the
decorative region 5 into a plurality of sections are straight lines
extending in the tire radial direction (the imaginary boundary line
32) and circles that are concentric with the tire circumferential
direction (the imaginary boundary line 34), but are not limited
thereto. The form and disposal position of the imaginary boundary
lines that divide the decorative region 5 into a plurality of
decorative portions is not particularly limited, provided that the
imaginary boundary lines can divide said region into a plurality of
portions in the tire circumferential direction and the tire radial
direction, respectively. That is, the disposal pattern in the
decorative region 5 is not particularly limited, provided that a
plurality of the decorative portions is disposed in the tire radial
direction and the tire circumferential direction, respectively.
[0054] Hereinafter, other examples of the decorative region will be
explained using FIGS. 5A to 5F. FIGS. 5A to 5F are explanatory
drawings, each illustrating a portion of other examples of the
decorative region. Note that in FIGS. 5A to 5F, only a portion
having a constant width in the tire circumferential direction of
the decorative region is depicted, but, as illustrated in FIG. 1,
each of the decorative regions is disposed throughout all regions
in the tire circumferential direction.
[0055] The decorative region 60 illustrated in FIG. 5A is a toric
region surrounded by the outer ring 52 and the inner ring 53. The
decorative region 60 is divided into a plurality of sections by
multiple imaginary boundary lines 62 and multiple imaginary
boundary lines 64. The imaginary boundary lines 62 are curved
(arcing) imaginary lines, formed by bending straight lines
extending in the tire radial direction so as to bend in a convex
direction in the tire circumferential direction, and are formed at
a constant pitch in the tire circumferential direction. First end
portions of the imaginary boundary lines 62 are located at the
outer ring 52 and second end portions are located at the inner ring
53. In other words, the imaginary boundary lines 62 are curved
lines extending from edge to edge of the decorative region 60 in
the tire radial direction. The imaginary boundary lines 64 are
imaginary lines that are extended in the tire circumferential
direction and are concentric with the outer ring 52 and the inner
ring 53, and are formed at a constant pitch in the tire radial
direction. The decorative region 60 is divided into a plurality of
sections in the tire radial direction by the outer ring 52, the
inner ring 53, and the imaginary boundary lines 64, and is divided
into a plurality of sections in the tire circumferential direction
by the imaginary boundary lines 62. In the decorative region 60,
each region surrounded in the tire circumferential direction by two
of the imaginary boundary lines 64, the imaginary boundary line 64
and the outer ring 52, or the imaginary boundary line 64 and the
inner ring 53; and surrounded in the tire radial direction by two
of the imaginary boundary lines 62 constitutes a decorative portion
69.
[0056] The decorative region 70 illustrated in FIG. 5B is a toric
region surrounded by the outer ring 52 and the inner ring 53. The
decorative region 70 is divided into a plurality of sections by
multiple imaginary boundary lines 72 and multiple imaginary
boundary lines 74. The imaginary boundary lines 72 are curved
imaginary lines, formed by bending straight lines extending in the
tire radial direction so as to bend in concave/convex directions in
the tire circumferential direction, and are formed at a constant
pitch in the tire circumferential direction. First end portions of
the imaginary boundary lines 72 are located at the outer ring 52
and second end portions are located at the inner ring 53. In other
words, the imaginary boundary lines 72 are curved lines extending
from edge to edge of the decorative region 70 in the tire radial
direction. The imaginary boundary lines 74 are imaginary lines that
are extended in the tire circumferential direction and are
concentric with the outer ring 52 and the inner ring 53, and are
formed at a constant pitch in the tire radial direction. The
decorative region 70 is divided into a plurality of sections in the
tire radial direction by the outer ring 52, the inner ring 53, and
the imaginary boundary lines 74, and is divided into a plurality of
sections in the tire circumferential direction by the imaginary
boundary lines 72. In the decorative region 70, each region
surrounded in the tire circumferential direction by two of the
imaginary boundary lines 74, the imaginary boundary line 74 and the
outer ring 52, or the imaginary boundary line 74 and the inner ring
53; and surrounded in the tire radial direction by two of the
imaginary boundary lines 72 constitutes a decorative portion
79.
[0057] The decorative region 80 illustrated in FIG. 5C is a toric
region surrounded by the outer ring 52 and the inner ring 53. The
decorative region 80 is divided into a plurality of sections by
multiple imaginary boundary lines 82 and multiple imaginary
boundary lines 84. The imaginary boundary lines 82 are inclined
straight imaginary lines, formed by inclining straight lines
extending in the tire radial direction at a prescribed angle with
respect to the tire radial direction, and are formed at a constant
pitch in the tire circumferential direction. First end portions of
the imaginary boundary lines 82 are located at the outer ring 52
and second end portions are located at the inner ring 53. In other
words, the imaginary boundary lines 82 are straight lines extending
from edge to edge of the decorative region 80 in the tire radial
direction. The imaginary boundary lines 84 are imaginary lines that
are extended in the tire circumferential direction and are
concentric with the outer ring 52 and the inner ring 53, and are
formed at a constant pitch in the tire radial direction. The
decorative region 80 is divided into a plurality of sections in the
tire radial direction by the outer ring 52, the inner ring 53, and
the imaginary boundary lines 84, and is divided into a plurality of
sections in the tire circumferential direction by the imaginary
boundary lines 82. In the decorative region 80, each region
surrounded in the tire circumferential direction by two of the
imaginary boundary lines 84, the imaginary boundary line 84 and the
outer ring 52, or the imaginary boundary line 84 and the inner ring
53; and surrounded in the tire radial direction by two of the
imaginary boundary lines 82 constitutes a decorative portion
89.
[0058] The decorative region 90 illustrated in FIG. 5D is a toric
region surrounded by the outer ring 52 and the inner ring 53. The
decorative region 90 is divided into a plurality of sections by
multiple imaginary boundary lines 92 and multiple imaginary
boundary lines 94. The imaginary boundary lines 92 are inclined
straight imaginary lines, formed by inclining straight lines
extending in the tire radial direction at a prescribed angle with
respect to the tire radial direction, and are formed at a constant
pitch in the tire circumferential direction. First end portions of
the imaginary boundary lines 92 are located at the outer ring 52
and second end portions are located at the inner ring 53. In other
words, the imaginary boundary lines 92 are straight lines extending
from edge to edge of the decorative region 90 in the tire radial
direction. The imaginary boundary lines 94 are inclined straight
imaginary lines, formed by inclining straight lines extending in
the tire radial direction at a prescribed angle opposite the
imaginary boundary lines 92 with respect to the tire radial
direction, and are formed at a constant pitch in the tire
circumferential direction. First end portions of the imaginary
boundary lines 94 are located at the outer ring 52 and second end
portions are located at the inner ring 53. In other words, the
imaginary boundary lines 94 are straight lines extending from edge
to edge of the decorative region 90 in the tire radial direction.
The region between the outer ring 52 and the inner ring 53 of the
decorative region 90 is divided into a plurality of sections by two
of the imaginary boundary lines 92 and two of the imaginary
boundary lines 94. Sections of the decorative region 90 contacting
the outer ring 52 are divided from other sections by the outer ring
52, one of the imaginary boundary lines 92, and one of the
imaginary boundary lines 94. Sections of the decorative region 90
contacting the inner ring 53 are divided from other sections by the
inner ring 53, one of the imaginary boundary lines 92, and one of
the imaginary boundary lines 94. As described above, in the
decorative region 90, each region surrounded by two of the
imaginary boundary lines 92 and two of the imaginary boundary lines
94, the outer ring 52 and one of the imaginary boundary lines 92
and one of the imaginary boundary lines 94, or the inner ring 53
and one of the imaginary boundary lines 92 and one of the imaginary
boundary lines 94 constitutes a decorative portion 99.
[0059] The decorative region 100 illustrated in FIG. 5E is a toric
region surrounded by the outer ring 52 and the inner ring 53. The
decorative region 100 is divided into a plurality of sections by
multiple imaginary boundary lines 102 and one imaginary boundary
line 104. The imaginary boundary lines 102 are straight imaginary
lines extended in the tire radial direction and are formed at a
constant pitch in the tire circumferential direction. First end
portions of the imaginary boundary lines 102 are located at the
outer ring 52 and second end portions are located at the inner ring
53. In other words, the imaginary boundary lines 102 are straight
lines extending from edge to edge of the decorative region 100 in
the tire radial direction. The imaginary boundary line 104 is an
imaginary line that is extended in the tire circumferential
direction and is concentric with the outer ring 52 and the inner
ring 53, and is disposed at a midway point between the outer ring
52 and the inner ring 53. The decorative region 100 is divided into
two sections in the tire radial direction by the outer ring 52, the
inner ring 53, and the imaginary boundary line 104, and is divided
into a plurality of sections in the tire circumferential direction
by the imaginary boundary lines 102. In the decorative region 100,
each region surrounded in the tire circumferential direction by the
imaginary boundary line 104 and the outer ring 52 or the imaginary
boundary line 104 and the inner ring 53; and surrounded in the tire
radial direction by two of the imaginary boundary lines 102
constitutes a decorative portion 109.
[0060] The decorative region 110 illustrated in FIG. 5F is a toric
region surrounded by the outer ring 52 and the inner ring 53. The
decorative region 110 is divided into a plurality of sections by
multiple imaginary boundary lines 112, multiple imaginary boundary
lines 114 and multiple imaginary boundary lines 116. The imaginary
boundary lines 112 are inclined straight imaginary lines, formed by
inclining straight lines extending in the tire radial direction at
a prescribed angle with respect to the tire radial direction, and
are formed at a constant pitch in the tire circumferential
direction. First end portions of the imaginary boundary lines 112
are located at the outer ring 52 and second end portions are
located at the inner ring 53. In other words, the imaginary
boundary lines 112 are straight lines extending from edge to edge
of the decorative region 110 in the tire radial direction. The
imaginary boundary lines 114 are inclined straight imaginary lines,
formed by inclining straight lines extending in the tire radial
direction at a prescribed angle opposite the imaginary boundary
lines 112 with respect to the tire radial direction, and are formed
at a constant pitch in the tire circumferential direction. First
end portions of the imaginary boundary lines 114 are located at the
outer ring 52 and second end portions are located at the inner ring
53. In other words, the imaginary boundary lines 114 are straight
lines extending from edge to edge of the decorative region 110 in
the tire radial direction. The imaginary boundary lines 116 are
imaginary lines that are extended in the tire circumferential
direction and are concentric with the outer ring 52 and the inner
ring 53, and are formed at a constant pitch in the tire radial
direction. Additionally, a position in the tire radial direction of
the imaginary boundary line 116 passes through an intersection of
the imaginary boundary line 112 and the imaginary boundary line
114, which is located at the same position in the tire radial
direction. The region between the outer ring 52 and the inner ring
53 of the decorative region 110 is divided into a plurality of
sections by one of the imaginary boundary lines 112, one of the
imaginary boundary lines 114, and one of the imaginary boundary
lines 116. Sections of the decorative region 110 contacting the
outer ring 52 are divided from other sections by the outer ring 52,
one of the imaginary boundary lines 112, and one of the imaginary
boundary lines 114. Sections of the decorative region 110
contacting the inner ring 53 are divided from other sections by the
inner ring 53, one of the imaginary boundary lines 112, and one of
the imaginary boundary lines 114. As described above, in the
decorative region 110, each region surrounded by one of the
imaginary boundary lines 112, one of the imaginary boundary lines
114, and one of the imaginary boundary lines 116; the outer ring
52, one of the imaginary boundary lines 112, and one of the
imaginary boundary lines 114; or the inner ring 53, one of the
imaginary boundary lines 112, and one of the imaginary boundary
lines 114 constitutes a decorative portion 119.
[0061] As described above, the decorative region can have various
forms, defined by straight or curved imaginary boundary lines,
combinations of straight and curved imaginary boundary lines, or
the like. Additionally, it is sufficient that the decorative region
be divided into a plurality of sections in the tire radial
direction and the tire circumferential direction. That is, it is
sufficient that a plurality of decorative portions be formed at any
position that is on a straight line parallel with the tire radial
direction and that is concentric with the tire circumferential
direction, and it is not necessary that straight imaginary boundary
lines that are parallel with the tire radial direction and
imaginary boundary lines that are circles concentric with the tire
circumferential direction be provided.
[0062] Moreover, by forming the imaginary boundary line
systematically (e.g. in parallel at a constant pitch) as described
above in the embodiment, the decorative region can be provided with
a form in which an identical, repeating pattern of the decorative
portion is formed. As a result, camouflaging effects of
unevennesses can be further enhanced and the tire can be made to
appear more three-dimensional. Therefore, while it is preferable
that the imaginary boundary lines be formed systematically in the
decorative region as described above in the embodiment, the present
technology is not limited thereto. For example, in the decorative
region, the pitch and form of the imaginary boundary lines may vary
based on position, or may include decorative portions having
various forms. For example, a decorative region may be provided in
which a rectangular decorative portion, a pentagonal decorative
portion, and a decorative portion that is partially curved are
provided so as to be contiguous around a triangular decorative
portion.
[0063] Here, the ridge arrangement angle .alpha. of the decorative
portion is preferably not less than 20.degree. and not more than
160.degree. different from the ridge arrangement angle .alpha. of
the contiguous decorative portions. In other words, the ridge
arrangement angle .alpha. of the decorative portion and the ridge
arrangement angle .alpha. of the contiguous decorative portions are
preferably not less than 20.degree. and not more than 160.degree.
different. By configuring the ridge arrangement angle .alpha. of
the decorative portion and the ridge arrangement angle .alpha. of
the contiguous decorative portions to be not less than 20.degree.
and not more than 160.degree. different, camouflaging effects of
unevennesses can be further enhanced and the tire can be made to
appear more three-dimensional.
[0064] Additionally, unevennesses in the side wall portion 3 can be
further favorably camouflaged and the three-dimensional effect can
be further enhanced by configuring the pneumatic tire 1 so that the
imaginary boundary lines overlap, such as in this embodiment. Note
that it is not necessary that the imaginary boundary line of the
decorative portion overlap with the imaginary boundary line of the
contiguous decorative portion.
[0065] FIGS. 6 and 7 are enlarged side views illustrating other
examples of an area around a boundary between decorative portions.
With the decorative region illustrated in FIG. 6, an imaginary
boundary line 132a joining first end portions of ridges 123a in the
decorative portion 122c and imaginary boundary line 132b joining
second end portions of ridges 125a in the decorative portion 122d
are separated by a distance I.sub.1. Ridges are not formed between
the imaginary boundary line 132a and the imaginary boundary line
132b in the decorative region illustrated in FIG. 6. Next, with the
decorative region illustrated in FIG. 7, an imaginary boundary line
132d joining first end portions of ridges 123b in the decorative
portion 122e and an imaginary boundary line 132c joining second end
portions of ridges 125b in the decorative portion 122f are
separated by a distance I.sub.2. The ridges 123b and the ridges
125b are both formed between the imaginary boundary line 132c and
the imaginary boundary line 132d in the decorative region
illustrated in FIG. 7 or, rather, the ridges overlap.
[0066] When the first imaginary boundary line joining the end
portions of the ridges of a decorative portion that are on a side
adjacent to a contiguous decorative portion is separated from the
second imaginary boundary line joining end portions of the ridges
of the contiguous decorative portion on a side adjacent to the
first imaginary boundary line as illustrated in FIG. 6, or overlap
as illustrated in FIG. 7, the distance between the first imaginary
boundary line and the second imaginary boundary line (i.e. the
distance I.sub.1 or the distance I.sub.2) is configured to be less
than 1 mm. Thus, the effects described above can be obtained.
[0067] Additionally, as described in this embodiment, with the
pneumatic tire 1, ridge end portions of contiguous decorative
portions are formed so as to be disconnected and, therefore,
cracking and growth of cracks in the recesses of the ridges can be
suppressed and durability can be enhanced. With the pneumatic tire
1, the ridges of the decorative portion and the ridges of the
contiguous decorative portion preferably have a disconnected form,
because such a configuration leads to the effects described above
being obtained. However, alternately, the ridges of the decorative
portion and the ridges of the contiguous decorative portion may
have a connected form.
[0068] The decorative region preferably has not less than three
types and not more than twelve types of the decorative portions
having different ridge arrangement angles .alpha.. In other words,
the decorative region preferably has a configuration including a
combination of decorative portions having not less than three types
and not more than twelve types of ridge arrangement angles .alpha..
Thus, the effect of camouflaging the unevennesses of the side wall
portion 3 can be enhanced by providing decorative portions having
not less than three types of the ridge arrangement angles .alpha.,
and manufacturing costs can be reduced due to being able to reduce
the number of types of dies by providing decorative portions having
not more than twelve types of the ridge arrangement angles
.alpha..
[0069] Here, the decorative portions are preferably disposed in the
decorative region in the tire circumferential direction and/or the
tire radial direction in a combination where the ridge arrangement
angle .alpha. varies periodically. In other words, units of the
decorative portions are preferably disposed in rows in the tire
circumferential direction and/or the tire radial direction, said
unit being a combination of decorative portions in which the ridge
arrangement angle .alpha. varies at a predetermined pattern and
order. Thus, the tire can be made to appear more three-dimensional
by varying the ridge arrangement angle .alpha. in a periodic
manner.
[0070] Furthermore, a plurality of the decorative portions is
preferably disposed in the decorative region in the tire
circumferential direction and/or the tire radial direction, in
order of stepwise ascending or descending size of the ridge
arrangement angle .alpha.. In other words, the decorative portions
are preferably disposed in order of stepwise ascending or
descending size of the ridge arrangement angle .alpha.. Thus, the
tire can be made to appear more three-dimensional by varying the
ridge arrangement angle .alpha. in a step-wise manner.
[0071] FIG. 8 is an enlarged side view illustrating another example
of a decorative region of the pneumatic tire. Note that in FIG. 8,
decorative portions 222a, 222b, 222c, and 222d, which are in a
portion on the inner ring 53 side, of the decorative portions of
the decorative region 200 are depicted. A boundary on the inner
side in the tire radial direction of the decorative portions 222a,
222b, 222c, and 222d is the inner ring 53, and a boundary on the
outer side in the tire radial direction (boundary with another
decorative portion) is an imaginary boundary line 234.
Additionally, a boundary between contiguous decorative portions in
the tire circumferential direction of the decorative portions 222a,
222b, 222c, and 222d is an imaginary boundary line 232. For
example, the decorative portion 222a and the decorative portion
222b are separated in the tire circumferential direction by the
imaginary boundary line 232.
[0072] The decorative portion 222a includes a plurality of ridges
223a. The ridge arrangement angle of the ridges 223a is an angle
.alpha..sub.9. The ridge arrangement angle .alpha..sub.9 in this
embodiment is 70.degree.. The decorative portion 222b includes a
plurality of ridges 223b. The ridge arrangement angle of the ridges
223b is an angle .alpha..sub.10. The ridge arrangement angle
.alpha..sub.10 in this embodiment is 60.degree.. The decorative
portion 222c includes a plurality of ridges 223c. The ridge
arrangement angle of the ridges 223c is an angle .alpha..sub.11.
The ridge arrangement angle .alpha..sub.11 in this embodiment is
50.degree.. The decorative portion 222d includes a plurality of
ridges 223d. The ridge arrangement angle of the ridges 223d is an
angle .alpha..sub.12. The ridge arrangement angle .alpha..sub.12 in
this embodiment is 40.degree.. The tire can be made to appear more
three-dimensional by varying the ridge arrangement angle .alpha. of
the decorative portions constituting the decorative region in a
step-wise manner, as with the decorative region 200 illustrated in
FIG. 8.
[0073] Additionally, with the decorative region 200 illustrated in
FIG. 8, the ridge arrangement angle of the decorative portions that
are not depicted is decreased by 10.degree. with each contiguous
decorative portion (170.degree. follows 0.degree.). Thereby, the
decorative portions can be disposed in order of stepwise ascending
or descending size of the ridge arrangement angle .alpha..
Moreover, the decorative portions 222a, 222b, 222c, and 222d
constitute a unit, said unit being disposed in plurality in the
tire circumferential direction. Thus, a combination of decorative
portions in which the ridge arrangement angle .alpha. varies
periodically can be disposed.
[0074] Additionally, an area (area of a surface of the side wall
portion) of the decorative portion is preferably not less than 0.3
cm.sup.2 and not more than 10.0 cm.sup.2. By configuring the area
of the decorative portion to be not less than 0.3 cm.sup.2, the
number of decorative portions disposed in the decorative region can
be maintained to or less than a suitable number, and increases in
fabrication costs for creating the dies for forming the decorative
portions can be suppressed. By configuring the area of the
decorative portion to be not more than 10.0 cm.sup.2, camouflaging
effects of unevennesses in the side wall portion can be further
enhanced.
[0075] Additionally, preferably at least one of the decorative
portions included in the decorative region has a ridge length per
unit area different than the ridge length per unit area included in
the decorative portions. In other words, the decorative region
preferably is provided with a decorative portion that has a
different ridge length per unit area. Here, "ridge length per unit
area" refers to a total extending distance of the ridges included
in one unit area. Because the decorative region is provided with a
decorative portion having a different ridge length per unit area,
ridge density between decorative portions can be varied roughly and
finely, variations in light reflection can be more appropriately
caused, and camouflaging effects of unevennesses in the side wall
portion 3 can be enhanced. The decorative portions having the
different ridge length per unit area are preferably disposed in the
decorative region of the decorative region 5 so as to repeat in the
tire circumferential direction. Thus, the tire can be configured so
as to appear more three-dimensional. Note that by varying the
arrangement pitch of the ridges, the ridge length per unit area of
decorative portions included in the decorative region can be
adjusted. That is, by providing at least one decorative portion
that has an arrangement pitch p that is different from the
arrangement pitch p of the ridges included in the other decorative
portions, at least one decorative portion having a ridge length per
unit area that is different from the ridge length per unit area
included in the other decorative portions can be provided.
Additionally, the ridge length per unit area can be varied by
forming the lines of the ridges per decorative portion differently,
for example, into straight lines and curved lines.
[0076] FIG. 9 is an enlarged side view illustrating another example
of a decorative region of the pneumatic tire. Note that in FIG. 9,
decorative portions 322a, 322b, 322c, and 322d, which are in a
portion on the inner ring 53 side, of the decorative portions of
the decorative region 300 are depicted. A boundary on the inner
side in the tire radial direction of the decorative portions 322a,
322b, 322c, and 322d is the inner ring 53, and a boundary on the
outer side in the tire radial direction (boundary with another
decorative portion) is an imaginary boundary line 334.
Additionally, a boundary between contiguous decorative portions in
the tire circumferential direction of the decorative portions 322a,
322b, 322c, and 322d is an imaginary boundary line 332. For
example, the decorative portion 322a and the decorative portion
322b are separated in the tire circumferential direction by the
imaginary boundary line 332.
[0077] The decorative portion 322a includes a plurality of ridges
323a. The ridge arrangement angle of the ridges 323a is an angle
.alpha..sub.13. The ridge arrangement angle .alpha..sub.13 in this
embodiment is 70.degree.. Additionally, the arrangement pitch of
the ridges 323a of the decorative portion 322a is P.sub.1. The
decorative portion 322b includes a plurality of ridges 323b. The
ridge arrangement angle of the ridges 323b is an angle
.alpha..sub.14. The ridge arrangement angle .alpha..sub.14 in this
embodiment is 60.degree.. Additionally, the arrangement pitch of
the ridges 323b of the decorative portion 322b is P.sub.2. The
arrangement pitch P.sub.2 is a distance that is shorter than the
arrangement pitch P.sub.1. Thus, the ridges 323b of the decorative
portion 322b are more densely disposed than the ridges 323a of the
decorative portion 322a, and the ridge length per unit area of the
decorative portion 322b is longer than the ridge length per unit
area of the decorative portion 322a. The decorative portion 322c
includes a plurality of ridges 323c. The ridge arrangement angle of
the ridges 323c is an angle .alpha..sub.15. The ridge arrangement
angle .alpha..sub.15 in this embodiment is 50.degree..
Additionally, the arrangement pitch of the ridges 323c of the
decorative portion 322c is P.sub.3. The arrangement pitch P.sub.3
is a distance that is longer than the arrangement pitch P.sub.1.
Thus, the ridges 323c of the decorative portion 322c are more
widely disposed than the ridges 323a of the decorative portion
322a, and the ridge length per unit area of the decorative portion
322c is shorter than the ridge length per unit area of the
decorative portion 322a. The decorative portion 322d includes a
plurality of ridges 323d. The ridge arrangement angle of the ridges
323d is an angle .alpha..sub.16. The ridge arrangement angle
.alpha..sub.16 in this embodiment is 40.degree.. Additionally, the
arrangement pitch of the ridges 323d of the decorative portion 322d
is P.sub.4. The arrangement pitch P.sub.4 is a distance that is the
same as the arrangement pitch P.sub.2. The ridge length per unit
area of the decorative portion 322d is the same as the ridge length
per unit area of the decorative portion 322b. Because a decorative
portion is included in the decorative region 300 that has a ridge
length per unit area that is different from the ridge length per
unit area of the other decorative portions as illustrated in FIG. 9
or, in other words, because decorative portions are included in
which the ridge length per unit area varies, the tire can be made
to appear more three-dimensional.
[0078] Additionally, in a pneumatic tire, the decorative region is
preferably provided throughout all regions of the side wall portion
of the tire, as described above in the embodiment. Additionally,
unevennesses in the side wall portion 3 can be more favorably
camouflaged and the three-dimensional effect can be further
enhanced by configuring the pneumatic tire so that the decorative
region is provided in all regions thereof in the tire
circumferential direction. Note that the pneumatic tire may have a
configuration in which the decorative region is provided partially
in the tire circumferential direction, or may be provided in a
plurality so as to be separate. Additionally, in the embodiment
described above, an example was described in which only ridges were
formed in the decorative region, however, alphanumerics, marks, and
the like (i.e. alphanumerics, brand names, and the like for the
purpose of identifying the tire) may be formed therein. When
providing alphanumerics or marks in the decorative region, ridges
may be omitted from the portion where the alphanumerics or marks
are formed, or a configuration may be used in which only the
outlines of the alphanumerics or marks are left and ridges are
formed in the other portions (area within the alphanumerics, or the
like). Visibility of branding and the like can be enhanced by
disposing alphanumerics or marks of brands, or the like, in the
decorative region.
[0079] Next, the pneumatic tire will be explained in more detail
using test examples. In the test examples, a pneumatic tire having
a tire size of 205/55R16 91V and a rim size of 16.times.6.5 JJ was
used. Ridges that constitute decorative regions of a Conventional
Example, Comparative Examples, and Working Examples were formed in
regions corresponding to the decorative region 5 of a pneumatic
tire having the size described above. Each tire was then evaluated
based on various criteria.
[0080] In the pneumatic tire of the Conventional Example, multiple
ridges were formed in the decorative region. Note that the multiple
ridges formed in the decorative region were formed so that there
was a single ridge arrangement angle, that is, so that there was
one type of decorative portion in the decorative region. In other
words, the multiple ridges were all angled at the same ridge
arrangement angle.
[0081] In the test examples, pneumatic tires of Comparative
Examples 1 and 2 were evaluated as Comparative Examples. The
pneumatic tire of Comparative Example 1 was provided with imaginary
boundary lines (boundary lines) so as to form a vertical striped
pattern. That is, only imaginary boundary lines extending in the
tire radial direction were provided as the imaginary boundary
lines, a plurality of decorative portions were provided in the tire
circumferential direction in the decorative region, and one
decorative portion was provided in the tire radial direction.
Moreover, two types of decorative portions were disposed in the
decorative region so as to alternate in the tire circumferential
direction (circumferential direction). Additionally, only one type
of decorative portion was provided in the decorative region in the
tire radial direction (radial direction). A difference in the ridge
arrangement angles of contiguous decorative portions (difference
between the ridge arrangement angle .alpha. of one decorative
portion and the ridge arrangement angle .alpha. of a contiguous
decorative portion) was 20.degree.. The area of one of the
decorative portions in the decorative region was 15.0 cm.sup.2. In
the decorative region, the ridges of the decorative portion and the
ridges of the contiguous decorative portion are not connected.
Moreover, in the decorative region, there is no decorative portion
with a different total ridge length per unit area or, in other
words, the total ridge lengths per unit area of all of the
decorative portions are the same.
[0082] The pneumatic tire of Comparative Example 2 was provided
with imaginary boundary lines (boundary lines) so as to form a
horizontal striped pattern. That is, only imaginary boundary lines
extending in the tire circumferential direction were provided as
the imaginary boundary lines, a plurality of decorative portions
was provided in the tire radial direction in the decorative region,
and one decorative portion was provided in the tire circumferential
direction. In other words, the decorative region was configured so
that a plurality of ring-shaped decorative portions having
differing sizes in the radial direction was provided. Moreover, two
types of decorative portions were disposed in the decorative region
so as to alternate in the tire radial direction (radial direction).
Additionally, only one type of decorative portion was provided in
the decorative region in the tire circumferential direction
(circumferential direction). A difference in the ridge arrangement
angles of contiguous decorative portions (difference between the
ridge arrangement angle .alpha. of one decorative portion and the
ridge arrangement angle .alpha. of a contiguous decorative portion)
was 20.degree.. In the decorative region, the ridges of the
decorative portion and the ridges of the contiguous decorative
portion are not connected. Moreover, in the decorative region,
there is no decorative portion with a different total ridge length
per unit area or, in other words, the total ridge lengths per unit
area of all of the decorative portions are the same.
[0083] Additionally, in the test examples, pneumatic tires of
Working Examples 1 to 7 were evaluated as Working Examples. The
pneumatic tire of Working Example 1 was provided with imaginary
boundary lines (boundary lines) so as to form a lattice pattern. In
other words, this pneumatic tire had a configuration in which both
imaginary boundary lines extending in the tire circumferential
direction and imaginary boundary lines extending in the tire radial
direction were provided as the imaginary boundary lines, and the
decorative portions were provided in the tire radial direction and
the tire circumferential direction, respectively, of the decorative
region. Moreover, two types of decorative portions were disposed in
the decorative region so as to alternate in the tire radial
direction (radial direction) and two types of decorative portions
were disposed in the decorative region so as to alternate in the
tire circumferential direction (circumferential direction). A
difference in the ridge arrangement angles of contiguous decorative
portions (difference between the ridge arrangement angle .alpha. of
one decorative portion and the ridge arrangement angle .alpha. of a
contiguous decorative portion) was 10.degree.. The area of one of
the decorative portions in the decorative region was 15.0 cm.sup.2.
In the decorative region, the ridges of the decorative portion and
the ridges of the contiguous decorative portion were connected.
Moreover, in the decorative region, there is no decorative portion
with a different total ridge length per unit area or, in other
words, the total ridge lengths per unit area of all of the
decorative portions are the same.
[0084] Other than changing the difference in the ridge arrangement
angles of contiguous decorative portions in the decorative region
to 20.degree., the pneumatic tire of Working Example 2 had the same
configuration as the pneumatic tire of Working Example 1. Other
than randomly disposing three types of decorative portions in the
decorative region in the tire radial direction (radial direction)
and randomly disposing three types of decorative portions in the
decorative region in the tire circumferential direction
(circumferential direction), the pneumatic tire of Working Example
3 had the same configuration as the pneumatic tire of Working
Example 2. Other than periodically disposing three types of
decorative portions in the decorative region in the tire radial
direction (radial direction) and periodically disposing three types
of decorative portions in the decorative region in the tire
circumferential direction (circumferential direction), the
pneumatic tire of Working Example 4 had the same configuration as
the pneumatic tire of Working Example 3. Other than configuring the
area of one decorative portion to be 4.0 cm.sup.2, the pneumatic
tire of Working Example 5 had the same configuration as the
pneumatic tire of Working Example 4. Other than being configured so
as to include a decorative portion having a different total ridge
length per unit area, the pneumatic tire of Working Example 6 had
the same configuration as the pneumatic tire of Working Example 5.
Other than being configured so that the ridges of one of the
decorative portions were not connected to the ridges of a
contiguous decorative portion, the pneumatic tire of Working
Example 7 had the same configuration as the pneumatic tire of
Working Example 6.
[0085] In these test examples, each of the pneumatic tires of the
Conventional Example, Comparative Examples, and Working Examples
was evaluated for the four criteria of appearance (of the carcass
splice portion), appearance (of the carcass folded up portion),
appearance (three-dimensional), and durability. Appearance (of the
carcass splice portion) was visually evaluated for the degree to
which the region corresponding to the carcass splice portion of the
side wall portion stood out. The evaluation results were converted
to index scores, with the index score for the Conventional Example
being 100. Larger index scores indicate superior appearance of the
side wall portion corresponding to the carcass splice portion.
Appearance (of the carcass folded up portion) was visually
evaluated for the degree to which the region corresponding to the
carcass folded up portion of the side wall portion stood out. The
evaluation results were converted to index scores, with the index
score for the Conventional Example being 100. Larger index scores
indicate superior appearance of the side wall portion corresponding
to the carcass folded up portion. Appearance (three-dimensional)
was visually evaluated for the degree to which a side ridge design
appeared to be three-dimensional. The evaluation results were
converted to index scores, with the index score for the
Conventional Example being 100. Larger index scores indicate
superior three-dimensional appearance. Here, "durability" refers to
durability against cracking in the decorative region. In these test
examples, cuts having a depth of 1.5 mm and a length of 5.0 mm were
formed in recesses between ridges at four locations (at equal
intervals) on the periphery of the tire. The pneumatic tires in
which the cuts described above are formed were inflated to an air
pressure of 120 kPa, and mounted on an internal drum tester. A load
equivalent to 88% of a maximum load capacity of each tire was
applied, and continued traveling was performed for 62 hours at a
speed of 81 km/h. Following the traveling, each of the pneumatic
tires was evaluated by measuring a growth ratio of the cuts. The
evaluation results were converted to index scores, with the index
score for the Conventional Example being 100. Larger index scores
indicate superior durability, and specifically indicate that crack
growth is suppressed. Note that in these performance tests,
pneumatic tires scoring 104 or higher are considered to be
superior, and pneumatic tires scoring in a range from 97 to 103 are
considered to be equivalent. The results of testing the four
criteria described above are shown in the following Tables 1 to
3.
TABLE-US-00001 TABLE 1 Conventional Comparative Comparative Example
Example 1 Example 2 Disposal of boundary lines -- Vertical
Horizontal striped striped pattern pattern Difference in smallest
ridge -- 20 20 angles of contiguous regions Number of types of
ridge arrangement angles Throughout 1 2 2 Radial 1 1 2 direction
Circumferential 1 2 1 direction Arrangement of ridge angle --
Alternating Alternating disposal Area of one decorative section --
15 -- (cm2) Presence/absence of Absent Absent Absent decorative
portion with different total ridge length per unit area
Relationship of ridge end -- Disconnected Disconnected portions of
contiguous sections Appearance Carcass splice 100 102 100 portion
Carcass folded 100 100 102 up portion Three-dimensionality 100 102
102 Durability 100 100 100
TABLE-US-00002 TABLE 2 Working Working Working Working Example 1
Example 2 Example 3 Example 4 Disposal of boundary lines
Lattice-form Lattice-form Lattice-form Lattice-form Difference in
smallest ridge 10 20 20 20 angles of contiguous regions Number of
types of ridge arrangement angles Throughout 2 2 3 3 Radial 2 2 3 3
direction Circumferential 2 2 3 3 direction Arrangement of ridge
angle Alternating Alternating Random Periodic disposal Area of one
decorative section 15 15 15 15 (cm2) Presence/absence of Absent
Absent Absent Absent decorative portion with different total ridge
length per unit area Relationship of ridge end Connected Connected
Connected Connected portions of contiguous sections Appearance
Carcass splice 104 105 106 107 portion Carcass folded 104 105 106
107 up portion Three-dimensionality 104 105 106 107 Durability 100
100 100 100
TABLE-US-00003 TABLE 3 Working Working Working Example 5 Example 6
Example 7 Disposal of boundary lines Lattice-form Lattice-form
Lattice-form Difference in smallest ridge 20 20 20 angles of
contiguous regions Number of types of ridge arrangement angles
Throughout 3 3 3 Radial 3 3 3 direction Circumferential 3 3 3
direction Arrangement of ridge angle Periodic Periodic Periodic
disposal Area of one decorative section 4 4 4 (cm2)
Presence/absence of Absent Present Present decorative portion with
different total ridge length per unit area Relationship of ridge
end Connected Connected Disconnected portions of contiguous
sections Appearance Carcass splice 108 110 110 portion Carcass
folded 108 110 110 up portion Three-dimensionality 108 110 110
Durability 100 100 104
[0086] It is clear from Tables 1 to 3 that, compared to the
Conventional Example and the Comparative Examples, the Working
Examples were evaluated to be superior in terms of the each of the
three appearance criteria. As described above, it is clear that the
quality of the appearance of a tire can be enhanced while tire
performance is maintained with the pneumatic tire of the present
technology. Moreover, it is clear from the results of Working
Examples 6 and 7 that durability can be enhanced by providing a
form in which the ridges of contiguous decorative portions are
disconnected.
* * * * *